The present invention relates to air bag devices which inflate and spread for protecting vehicle occupants in cases of emergency. In particular, the present invention relates to an air bag device in which undesirable effects of heat on a bag body, which is generated when an inflator ignites, can be suppressed, and in which components can be assembled easily.
At present, vehicles are generally provided with air bag devices for drivers, for passengers, and for rear seats, side air bags, and the like, which are used for protecting occupants in cases of emergency. Each air bag device generally includes a bag, an inflator which supplies gas to inflate the bag, a retainer for retaining the bag and the inflator, and the like as a module to be mounted to the vehicle.
FIGS. 5(A), 5(B), and 5(C) are schematic cross-sectional views of known air bag devices.
In FIG. 5(A), an air bag device 100 includes a box-shaped metallic retainer 110. The retainer 110, when used in an air bag device for a passenger""s seat, is disposed in an instrument panel of the automobile. A cylindrical inflator 105 is disposed in the bottom of the retainer 110. The inflator 105 may be appropriately selected from a compressed-gas-type inflator and a combustion-gas-type inflator. The inflator 105 is fixed to the retainer 110 by bolts and nuts (not shown).
A bag 101 is mounted to the retainer 110 with a holding portion (open end) 101a of the bag 101 being affixed at an upper opening of the retainer 110 by bolts and nuts 107. Regarding the bag 101, only the holding portion 101athereof in inflating states is shown in the drawings. In an emergency, spreading gas is supplied into the bag 101 through gas outlets disposed on the side of the inflator 105. The bag 101 is generally folded and is received in the retainer 110.
When a combustion-gas-type inflator is used as the inflator 105 in the air bag device 100, it is likely that the holding portion 101a of the bag 101 is deformed due to the heat generated by the gases from the inflator 105, thereby causing leakage of the combustion gas. Therefore, in the known air bag device 100, a predetermined distance is provided between the position at which the holding portion 101a of the bag 101 is mounted (the level of the bolts-nuts 107) and the inflator 105.
However, when the holding portion 101a of the bag 101 and the inflator 105 are separated by a certain distance, the height of the retainer 110 is increased, and the overall air bag device 100 is enlarged. Although a compressed-gas-type inflator, which generates little heat, may be used as the inflator 105 so as to minimize the above distance, freedom of the selection of inflator becomes limited due to the increased size of the device.
In order to overcome the aforementioned drawbacks, the following modifications, for example, have been given to the known air bag devices.
As shown in FIG. 5(B), the retainer 110 is provided with a mid plate (diffuser) 116 between the holding portion 101a of the bag 101 and the inflator 105. By providing the mid plate 116, spreading gas jets out concentrating in one direction (to the center of the bag 101). Therefore, heat generated when the inflator 105 fires does not directly affect the holding portion 101a of the bag 101.
In FIG. 5(C), a protection cloth 117 is provided at the open end of the bag 101. The deformation of the holding portion 101a of the bag 101 is suppressed by the protection cloth 117.
However, with the arrangements shown in FIGS. 5(B) and 5(C), additional components (i.e., the mid plate 116 or the protection cloth 117) are required. Therefore, there is a drawback in that costs for components are increased and the number of manufacturing processes is also increased.
Moreover, in each of the air bag devices shown in FIGS. 5(A) to 5(C), the holding portion 101a of the bag 101 and the inflator 105 are individually affixed to the retainer 110 by using the bolts-nuts 107 and other bolts and nuts (not shown), respectively, whereby the assemble of the components is complex.
Another airbag device is shown in U.S. Pat. No. 6,173,988, which is incorporated by reference herein.
Accordingly, an object of the present invention is to provide an air bag device in which undesirable effects of heat, which is generated when the inflator fires, onto a bag body can be reduced and components of the air bag device can be assembled easily.
According to the present invention, an air bag device is provided. The device includes an inflatable bag and an inflator for supplying gas to expand the bag. A retainer is provided for retaining the bag and the inflator. A plate is also provided for fixing the inflator to the retainer and the bag to the retainer at a holding portion of the bag. The plate includes a mechanism disposed between the plate and the inflator for suppressing the transmission of heat from the inflator to the plate.
The inflator may be cylindrical and the plate may include an inner face along the cylindrical outer face of the inflator. The mechanism may include a bead formed on the inner face of the plate and positioned to be in contact with the cylindrical outer face of the inflator.
According to an alternative embodiment of the present invention an airbag device is provided. The airbag includes an open end; an inflator for supplying gas into the open end of the bag; a retainer for holding the inflator; and a plate connected to the retainer wherein the inflator is positioned between the plate and the retainer and the open end of the bag is fixed between the retainer and the plate. The plate includes a portion projecting toward the inflator to reduce the conduction of heat from the inflator to the plate.
An air bag device having an inflator positioned between a retainer and a plate, wherein an open end of an inflatable airbag is secured between the retainer and the plate, and wherein contact between the plate and the inflator is limited to contact between a projecting portion of the plate and the inflator.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only, and are not restrictive of the invention as claimed.